All the reviews point to Michelin Pilot Sport 4’s but they are expensive
This is my shortlist
Avon ZV7
Falken ZE914
Michelin Pilot Sport 4
Toyo Proxes T1 Sport
Yokohama Advan Sport V105 or V103
Continental Premium Contact 6
I have Michelin Pilot Sport 4S on the Plus 8: a big improvement on the Avon ZZ3 tyres it came with.
The Roadster had Avon ZZ3 as well, I'd probably have gone for Avons again, but they don't do either the ZZ5 or ZV7 in the correct sizes for the front fitting on the Plus 8.